I'm basically using Perl to "cat long_file_list > mergedFile". My program runs on Windows and I would use DOS>type for the job but my argument list is too long. So I've written a tiny Perl program for the process and it works nicely for small ASCII files but fails for large binary files. Somehow Perl adds extra characters to the merged binary file as verified by DOS>dir. I'm using ActiveState Perl v5.16.3 built for MSWin32-x64-multi-thread. Why does this program fail for large binary file inputs and is there a better way to do it? And here is the program: 
 

#!perl -w
#test Perl's I/O for merging binary files



#global initializations 
   use strict;    #require variable declaration 
   sub merge_pieces (\@$);    #function prototype 

#try the function 
   my @inList =  qw < in1 in2 in3 >; 
   merge_pieces @inList, "out";



#function:  merge files to create 1 overall file 
   #input 1:  $pieceList, reference to a list of file pieces 
   #input 2:  $outName, name of the merged file 
sub merge_pieces (\@$)
{
   #get function inputs 
   my ($pieceList, $outName) = @_; 

   #user message 
   print "Reconstituting file $outName from \n"; 

   #open output file 
   open my $fOut, ">", $outName   
      or die "Unable to open file $outName for writing:  $! \n"; 

   #loop for all input files 
   foreach my $toRead (@$pieceList)
   {
      #open file 
      open my $input, "<", $toRead
         or die "Unable to open file $toRead for reading:  $! \n"; 

      #user message 
      print "   $toRead \n"; 

      #read and write entire file 
      while (<$input>) 
         { print $fOut $_} 
   }
}

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In reply to Binary file I/O problem by DavidZ

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